Sulfonic acid surface active agent and method of preparation



Patented Apr. 10, 1951 SULFONIC ACID SURFACE ACTIVE AGENT AND METHOD OF PREPARATION Glen W. Hedrick, Glen Ellyn, Ill., assignor to E. F. Houghton and Company,

Philadelphia,

Pa., a corporation of Pennsylvania No Drawing. Application October 12, 1948,

Serial No. 54,209

11 Claims. 7 l The present invention relates to novel surface active agents and more particularly it relates to surface active agentshaving marked detergent properties, as well as other desirable properties,

comprising a new type of chemical substance, namely, the water-soluble salts of a benzoyl sulpho propionic acid ester as more fully described hereinafter. This application is a continuation in-part of application Serial No. 626,438, filed November 2, 1945, now abandoned.

The principal object of the invention is to provide surface active agents having outstanding detergent properties, which agents may be used wherever such properties are desired, for example, in processing textile fibres and fabrics, leather, paper, and other fibrous materials, in cleaning processes, such as general household cleaning, material cleaning, dishwashing, and the like. and in frothing, emulsifying, emulsion breaking, flotation, and other processes.

Another object is to provide compounds having detergent properties which may be used to advantage in neutral, alkaline, or acid media,- either alone or in combination with other detergent materials.

Other objects, including the provision of a novel method of producing the surface active agents of the invention, will be apparent from a consideration of the specification and the claims.

As indicated above, the surface active agents of the present invention, possessing detergent properties, comprise the water-soluble salts of the benzoyl sulpho propionic acid esters, the benzoyl radical being defined as a radical of the type RCO- where R is a substituted phenyl radical of the type hereinafter set forth.

The surface active agents of the present invention are represented by the formula:

A R1 O O wthatmm R, SIO3M where R1 is an alkyl group containing from to carbon atoms; where R'1 is selected from the group consisting of hydrogen and a methyl group;

Where A is selected from the group consisting of atoms; where M is a cation providing water solubility to the product; and where the total number of carbon atoms of R2 plus carbon atoms in substituted alkyl groups (R1 and R1) on the phenyl nucleus is at least 10 but-not more than 16.

Thus, in the above formula, the group A B1 I may be written as X which represents a phenyl derivative selected from the group consisting of monoalkyl phenyl and monochloromonoalkyl phenyl, the alkyl group of which-containsfrom 10 to 15 carbon atoms, and monoalkyltolyl, wherein the substituted alkyl group contains from 10 t014 carbon atoms, and where the number of carbon atoms supplied by the substituted alkyl group attached to the phenyl nucleus, and a methyl group if present, provide, with the carbon atoms supplied by R2, a total of at least 10 but not more than 16 carbon atoms.

'In the above formula, no attempt has been made to indicate to which of the two carbon atoms in the ethylene (B) group the sulpho group (-SO3M) isattached. Themost practical chemical processes, however, for introducing the sulpho group into this ethylene linkage are believed to produce mixtures rather than pure alpha or pure beta derivatives. Generally, while the alpha derivative is believed to predominate, the location of the sulpho group is immaterial since it mustexert a similar hydrophilic action on the molecule either in the alpha or the beta position, and it is to be understood that both the alpha and beta compounds, and mixtures thereof, are within the scope of the invention. j

As pointed out in connection with the formula, M is a cation rendering the compound watersoluble, for example, an alkali metal such as sodium or potassium, the ammonium radical, and the like.

The products of the present invention thus embody not only a benzoyl or chlorbenzoyl group but also a definite number of exterior or external carbon atoms in the various Rgroups. As stated, these externalcarbon atoms must total at least 10 and not more than 16. Some of these external carbon atoms are provided by an alkyl ester group, R2. The major portion of these external carbon atoms are provided by a substituted alkyl group, or alkyl group plus a methyl group,-

attached to the phenyl nucleus, and as indicated, the substituted alkyl group contains at least 10 but no more than 15 carbon atoms. From the standpoint of the present invention, it is relatively immaterial whether the various alkyl groups are straightor branched-chain alkyl groups. A chlorine atom may also be attached to the phenyl nucleus without altering the properties of the compound significantly. Since the alkyl group attached to the phenyl nucleus contains more than 10 but not more than 15 carbon atoms, and since R2 contains no more than 6 carbon atoms, and since the total number of external carbon atoms ranges from 10 to 1b}, for each ester group (R2) employed,-there is a definite range of carbon atoms'that may be present in the groups attached to the phenyl nucleus and vice versa. For example, if there is a tetradecyl group attached to the phenyl nucleus (1. e., a

is tetradecyl phenyl or tetradecylchlorophenyl) A R1 I is decyl tolyl) the ester group is restricted to the methyl through the amyl groups.

While numerous specific compounds may be prepared by the methods hereinafter described corresponding to the formula given for the compounds of the invention, they will possess marked detergent properties, making them available for use as surface active agents in the various industrial fields. This is because such compounds embody the basic structure hereinabove set forth and contain external carbon atoms Within the stated limits, and the specific examples hereinafter set forth demonstrate the fact that such compounds possess marked wetting properties.

The compounds of the invention possessing detergent properties to the highest degree are those corresponding to the formula:

Crafts acylation type of reaction, with the anhydride of a four carbon atom dicarboxylic aliphatic'r acid, i. e., maleicanhydride or succinic anhydride; esterifying the resulting acid; and then converting the ester into the sulpho derivative, as will be further discussed hereinafter. Another, but not preferred, method of preparing the products of the present invention is by condensing a half ester-half acid chloride of the four carbon atom dibasic acid with the phenyl derivative to provide the ester, and then converting the ester into the sulpho derivative.

organic synthesis.

benzoyl acrylic acid ester.

In preparing the benzoyl derivative, the desired phenyl derivative furnishing not only the phenyl or monochlorophenyl nucleus, but also the substituted alkyl group, or alkyl and methyl groups, is reacted by a Friedel-Crafts acylation reaction with a molar equivalent of the anhydride. The phenyl derivatives may be obtained from any source, but are ordinarily prepared by For example, the alkylated phenyl derivatives may be obtained by condensing benzene with an alkyl halide or with an aliphatic olefin by a preliminary Friedel-Crafts alkylation reaction. Since R1 is a relatively long alkyl group, it is advantageously obtained from a petroleum source, for example, by cracking petroleum oil to obtain olefins or by the polymerization of olefins of low molecular weight. The keryl benzenes and keryl chlorobenzenes may be prepared by chlorinating kerosene (the petroleum fraction boiling between about 350 F. and 500 F.), and then condensing the chlorinated kerosene directly or through the olefin produced therefrom with benzene or chlorobenzene in the presence of anhydrous aluminum chloride or other appropriate catalyst.

Examples of the phenyl derivatives that may be used in the preparation of the benzoyl derivatives in accordance with the present invention are: the monoalkyl benzenes such as the decyl benzenes, the dodecyl benzenes such as lauryl benzene, the tridecyl benzenes, the tetradecyl benzenes, the pentadecyl benzenes, the various keryl benzenes, the keryl group of which averages from 10 to 15 carbon atoms; the corresponding alkylated chlorobenzenes; and the like; the mono alkyl toluenes such as the decyl toluenes, the dodecyl toluenes, such as lauryl toluene, the tetradecyl toluenes, the various keryl toluenes the keryl group of which averages from 10 to 14 car bon atoms; and the like.

The anhydride of the four carbon atom dicarboxylic aliphatic acid may be the unsaturated maleic anhydride or the saturated succinic anhydride, When maleic anhydride is employed, the benzoyl compound prior to sulphonation is a Upon sulphite addition, the double bond is saturated and the product is a water-soluble salt of a benzoyl sulpho propionic acid ester, wherein the $03M group has become attached to one of the carbon atoms of the CH=CH- group, and a hydrogen atom to the other. In the case of succinic anhydride, the benzoyl derivative of propionic acid is formed as a result of the Friedel-Crafts reaction, and a hydrogen atom attached either to the alpha or beta carbon atom must be substituted by the sulpho group as hereinafter described.

The reaction between the phenyl derivative and the anhydride to form the corresponding benzoyl acrylic or propionic acid is brought about, as has been stated above, by a Friedel-Crafts acylation reaction and any of the various expedients used in that type of reaction may be employed in the production of the benzoyl compound. Advantageously, the condensation is brought about by condensing the phenyl derivative with approximately a molar equivalent of the anhydride in a suitable solvent with anhydrous or substantially anhydrous aluminum chloride. Since the phenyl derivatives employed are high boiling liquids, the use of a suitable inert solvent such as carbon disulphide, orthodichlorobenzene, methylene chloride, ethylene chloride, and tetrachloroethane is preferred.

T p nyl deri fl iil t @1 6 the anhydride may chloride added thereto, preferably gradually over a period of time, or the phenyl derivative may be mixed with a portion or all of the aluminum chloride and the anhydride and solvent may then be added, preferably gradually, followed by the addition of further amounts of aluminum chloride, if required. Other procedures for bringing together the phenyl derivative, the anhydride, the solvent, and the aluminum chloride may of course be used, if desired. The reaction, at least at the start, is. exothermic and hydrogen chloride is evolved as the reaction proceeds. The reacting mixture is generally maintained at a temperature in the range from about 20 C. to about 65 C. vby cooling at the start and by heating subsequently if necessary, and it is advantageous to agitate the mixture during the reaction.

When the condensation is completed, which may be determined by cessation of the evolution .of the hydrogen chloride, the mass may be poured into ice, water, and a small amount of mineral acid, keeping the mass cold as is the usual practice in the type of reaction, and the mixture may be agitated until the aluminum chloride complex is decomposed. The condensation product which is in solution in the solvent may then be separated from the aqueous phase and washed with water and mineral acid to remove the salts of aluminum.

The benzoyl acrylic or propionic acid may be isolated by removing the solvent by distillation. The acid may be purified by dissolving it in a solution of a suitable alkali, such as soda ash. filtering to remove any insoluble material and precipitating the acid by the addition of mineral acid.

In one procedure, the phenyl derivative is dis-- solved in an inert solvent and about one molecular equivalent of maleic anhydride is added to the solution. The mixture is heated to a temperature at which the aluminum chloride complex remains dispersed, for example, to about 40 C. and is maintained between that temperature and about 50 C. during the reaction. The aluminum chloride (about 2 molecular equivalents) is added gradually, for example, in portions during the reaction, and the mass is agitated during the reaction. When the reaction is complete, which may require several hoursfor example, six hours-the aluminum chloride complex is decomposed and the acid isolated as above described.

In a more preferred procedure, the aluminum chloride, anhydride, and a chlorinated solvent are mixed, and the mixture is agitated and becomes uniform. The phenyl derivative is gradually added at a temperature between about 40 C. and about 50 C., and after the addition is completed the mixture is stirred for a short period at a temperature between about 40 C. and about 60 C. The aluminum chloride complex is decomposed and the acid isolated as above-described.

The benzoyl acrylic or propionic acid is esterified with a compound providing the desired R2 group, and the resulting ester then converted to the sulpho derivative. The alkyl ester of the acid may be prepared by any of the suitable esterifying reactions.

In one type of method, the ester is formed by reacting the acid with one molecular equivalent of the aliphatic alcohol corresponding to the alkyl ester desired in the presence of a solvent and an esterifying catalyst such as concentrated sulphuric acid, benzeneor toluene-sulphonic acid. Preferably, the solvent is one which like toluene, boils slightly above the boiling point of water.

The mixture of the benzoyl acrylic or propionic acid, the alcohol, the solvent, and the esterification catalyst are boiled and the water formed by the esterification reaction is removed. After the esterification reaction has been completed,

the ester, which is in solution in the solvent, may

be washed with water, followed in some cases by dilute alkali to remove ay unconverted acid and the traces of catalyst. The ester may be isolated by removing the solvent by steam distillation, distillation at atmospheric pressure, or by evaporation in vacuo.

In another type of esterification procedure, to produce compounds in which R2 is a small alkyl group, the ester of the benzoyl acrylic or propionic acid may be obtained by dissolving the acid in a solvent such as toluene, benzene, chlorbenzene, orthodichlorobenzene, carbon tetrachloride, tetrachlorethane, and the like. The acid is then converted into a salt and the ester formed by reaction with an alkyl sulphate, the alkyl group of which corresponds to the ester desired. In such a process, the salt is advantageously formed by the additionof a slurry of soda ash in water, and in such a case, foaming occurs due to the evolution of carbon dioxide, and the mass. becomes thick and has the appearance of a clear gel. The reaction between the salt of the acid and the alkyl sulphate is exothermic and is completed within a few minutes, as shown by the fact that a sample mixed with water separates readily into two layers. The mass obtained as the result of the reac tion is made acid by the addition of mineral acid, is washed with water to remove the salts, and the ester is obtained upon removal of the solvent by steam or vacuum distillation.

The benzoyl acrylic or propionic acid ester may be converted into the sulpho derivative by any process by which the -SO3M group may be attached to one of the carbon atoms of the vinylene or ethylene chain of the acrylic or propionic acid ester. Preferably, when a benzoyl acrylic acid ester is employed, the sulphonation is brought about by reacting the ester with a bisulphite such as sodium, potassium, or ammonium bisulphite. In the sulphonation reaction, the ester is mixed with the bisulphite dissolved in water or other solvent, for example, a mixture of equal parts of water and ethyl alcohol. The bisulphite employed is suflicient to convert the ester into the sodium or other salt of the sulphonic acid, the use of a slight excess of the bisulphite often being advantageous. The mixture is advantageously heated in a closed container equipped with an agitator until the ester becomes completely soluble in water. The temperature of heating will depend on the particular ester being treated and usually a temperature between about C. and C. will be employed, and in many instances it will be desired to heat the mixture to boiling. The ester is rendered completely soluble in water by this treatment and the product formed is the sulphonic acid salt of the cation of the bisulphite. Thus, as stated in connection with the formula, M may be any cation which provides water-solubility, for example, an alkali metal ion, ammonium radical or the like.

Referring to the saturated benzoyl propionic acid ester, it may be first converted into a haloenated. derivative, for example, a, bromo compound, prior to sulphonation. In such conversion process, the ester is advantageously dissolved in a solvent and a small amount of ahalogenating catalyst such as phosphorus trichloride is 7 added. The halogen, for example, bromine, is then brought into contact with the solution, for instance, by adding liquid bromine drop-by-drop to the solution. Hydrogen halide is liberated and the reaction is completed in a short time. The halogenated derivative is isolated by evaporation of the solvent. The halogenated derivative thus prepared may then be sulphonated by reacting the halogen derivative with a sulphite, for example, sodium or potassium sulphite, to replace the halogen atom of the compound with the SO3M group. Advantageously, the reaction is brought about by refluxing an aqueous mixture of the reactants until the reaction has progressed to completion. As in the case of the product obtained by the previously described method of sulphonation, the sulphonated product may be provided with the desired cation represented by M.

In order to illustrate the invention further, the following; specific examples are given for the preparation of the compounds of the present invention. Three different procedures were employed in preparing the compounds of the examples, which are illustrated below as Methods A, B, and C, respectively. Each of the numerical examples, from 1 to 13, inclusive, was made according to one of these three methods and to avoid repetition of the details of the procedures, each of these examples is designated as to which method was followed. In each case is given either a measure of the compounds surface activity by showin wetting speeds at various concentrations in water determined by the time required to wet out a 5 gram skein of raw cotton yarn at 100 F. according to the standard Draves method, or a description of the compounds detergency properties, or both.

METHOD A The preparation of the methyl ester of kerylbenzoyl dodecylbenzoyl sulpho propionic acid, sodium salt To a mixture of 49 g. /2 mol) of maleic anhydride and 105 g. aluminum chloride, there are added 90 cc. ethylene chloride. The suspension is agitated and water cooled. After most of the solids have dissolved, 123 g. mol) of keryl benzene (dodecyl benzene) are added slowly. After the addition, the mixture is stirred for 30 minutes at 50 C. The material is then cooled and decomposed with a mixture of 450 g. crushed ice, 50 cc. of 66% sulphuric acid and cc. isopropanol. After most of the dark brown complex has been decomposed, the mixture is heated to reflux temperature. After five minutes of refiuxing, the material is split into two layers. The lower layer is discarded. The upper layer is then washed twice with 70 cc portions of 66% sulphuric acid. Seventeen cc. of methanol and 12 cc. of concentrated sulphuric acid are added to the ethylene chloride solution of the maleic anhydride condensate and the material is refluxed for 45 minutes. The lower layer is then drawn off and another 12 cc. of methanol and 8 cc. of concentrated sulphuric acid are added, and refluxing is continued for another 90 minutes. The lower layer is again drawn off and the solvent is distilled off from the organic solution. The lasttraces of solvent are removed under vacuumand heating is continued until the temperature within the liquid has risen to 125 C. The liquid is then allowed to cool somewhat and a solution of 1 g. sodium hydroxide and 55 g.

sodium bisulphite in 250 cc. of water is added to the oil. The mixture is stirred and heated to 95 C. The temperature is maintained there for one hour although the sulphonation reaction is usually completed after ten minutes. The product gave a wetting speed of 42 seconds at a concentration of .1%, and exhibited good detergency properties.

METHOD B The preparation of the n-butyl ester of kerylbenzoyl (dodecylbenzoyl) sulpho propionic acid, sodium salt To a mixture of 49 g. mol) maleic anhydride and 105 g. aluminum chloride, there are added 90 cc. of ethylene chloride- The suspension is agitated and water cooled. After most of the solids have dissolved, 123 g. /g mol) keryl benzene (dodecylbenzene) are added slowly. After the addition, the mixture is stirred for 30 minutes at 50 C. The material is then cooled and decomposed with a mixture of 500 g. crushed ice, 100 cc. 66% sulphuric acid, and 37 g. mol) n-butyl alcohol. The mixture is stirred for 90 minutes at room temperature. The lower layer is then drawn off. 1 cc. of concentrated sulphuric acid is added to the organic layer which is then refiuxed through a constant water separator for 2 hours or longer until practically all of the acid has been esterified. The solvent is distilled off until the temperature within the oil has reached 110 C. A solution of 52 g. sodium bisulphite and 1 g. sodium hydroxide in 110 cc. of water is added to the oil. The agitated mixture is heated to 105 C. and is maintained there for 15 minutes, after which time sulphonation is complete. The isolated product at a concentration of .1% in water, provided a wetting speed of 139 seconds.

METHOD C The preparation of the methyl ester of lccrylbenzoyl (tridecylbenzoyl) sulpho propionic acid, sodium salt dichlorobenzene, there are added gradually in small portions 1&0 g. of aluminum chloride. The

temperature is allowed to rise gradually to 50 C.60 C. where it is maintained until no more hydrogen chloride vapors are given off. The material is decomposed by pouring it over 1 kg. of crushed ice to which cc. of concentrated sulphuric acid had been added. The lower layer is drawn off and the top layer washed three times with 66% sulphuric acid. The acid solution is then esterified with methanol as described under Method A. The mineral acid content of the ester solution is carefully neutralized and the solvent removed by steam distillation. The ester is then sulphonated as described under Method A. At a concentration of .1%, the product gave a wetting speed of 48 seconds and exhibited good detergency properties.

Other water-soluble salts instead of the sodium salt, such as the potassium or ammonium salts, may be prepared by employing potassium or ammonium bisulphite in the above methods in place of the sodium bisulphite. These other watersoluble salts exhibit strong surface active properties, and may be used in a manner similar to the sodium salts.

In the following examples, the sodium salt of the benzoyl sulpho propionic acid ester is prepared, but as previously set forth, other watersoluble salts such as the potassium or the ammonium salts may be prepared by analogous procedures.

EXAMPLE 1 The salt of the methyl ester of lauryl benzoyl sulpho propionic acid was prepared following Method'A by first condensing lauryl benzene (2- dodecylbenzene) with maleic anhydride. The lauryl benzoyl acrylic acid thus formed was esterified with methanol, and the resulting'ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of .l%, the compound gave a wetting speed of 31 seconds, and possessed strong sudsing properties.

EXAMPLE 2 EXAlVIPLE 3 The salt of the ethyl ester of kerylbenzoyl (dodecylbenzoyl) sulpho propionic acid was prepared following Method A by first condensing kerylbenzene (dodecylbenzene) with maleic anhydride. The kerylbenzoyl acrylic acid thus formed was esterifiedwith ethyl alcohol, and the resulting ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of .1%, it gave a wetting speed of 96 seconds, and exhibited good detergency properties, particularly in water containing over 100 P. P. M. lime hardness.

EXAMPLE 4 The salt of the ethyl ester of kerylbenzoyl (tridecylbenzoyl) sulpho propionic acid was prepared following Method C by first condensing kerylbenzene (tridecylbenzene) with maleic anhydride. The kerylbenzoyl acrylic acid thus formed was esterified with ethyl alcohol, and the resulting ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of 2%, it gave a wetting speed of 100 seconds, and possessed good detergency properties in water containing 50 P. P. M. lime hardness.

EXAMPLE 5 The salt of the propyl ester of kerylbenzoyl (dodecylbenzoyl) sulpho propionic acid was prepared following Method A by first condensing kerylbenzene (dodecylbenzene) with maleic anhydride. The kerylbenzoyl acrylic acid thus formed was esterified with propyl alcohol, and the-resulting ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of .1%, it gave a wetting speed of 6'7 seconds and exhibited good detergency properties in water Containing 50 P. P. M. lime hardness.

EXAMPLE 6 The salt of the n-hexyl ester of decylbenzoyl sulpho propionic acid was prepared following Method B by first condensing decylbenzene (prepared by alkylating benzene-with chlorinated decane) with maleic anhydride. The decylbenzoyl acrylic acid thus formed was esterified with nhexyl alcohol, and the resulting ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of .l%, the compound gave a wetting speed of 35 seconds. It exhibited sudsing and cleaning properties in soft water using a concentration of 0.2%.

EXAMPLE 7 The salt of the methyl ester of keryl (tridecyl) monochlorobenzoyl sulpho propionic acid was prepared following Method A by first condensing keryl (tridecyl) monochlorobenzene with maleic anhydride. The kerylmonochlorobenzoyl acrylic acid thus formed Wasesterified with methanol, and the resulting ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of 0.2%, it gave good foaming properties, possessed hard water detergency, and wet-out cotton yarn readily.

EXAMPLE 8 The salt of the n-butyl ester of dodecylchlorobenzoyl sulpho propionic acid was prepared following Method B by first condensing dodecy1-,- chlorobenzene (kerychlorobenzene) With maleic anhydride. The dodecylcl'ilorobenzoyl acrylic acid thus formed was esterified with n-butyl alcohol, and the resulting ester was reacted with sodium bisuplhite to form the sulpho derivative. Ata concentration of .l%, it gave a wetting speed of 113 seconds, and showed moderate sudsing power.

EXAMPLE, 9"

The salt of the methyl ester of decyltoluoyl sulpho propionic acid was prepared following Method A by first condensing decyltoluene (prepared by alkylating toluene with. chlorinated deoane) with maleic anhydride." Thedecyltoluoyl acrylic acid thus formed was esterified" with,

methyl alcohol, and'the resulting ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of .2%, the compound exhibited good foaming properties, particularly in Water containing more than 100 P. P. M. lime hardness.

EXAIVEPLE 1c The salt of the methyl ester of dodecyltoluoyl sulpho propionic acid 'Was prepared followingv Method A by firstcondensing dodecyltoluenewith maleic anhydride. The dodecyltoluoyl acrylic acid thus formed was esterified with methyl I alcohol and the resulting ester was reacted with sodium bisulphite to form the sulpho derivative.

At a concentration of 0.1%, it gave a wettin speed of 45 seconds, and exhibited good sudsing and detergency properties. in soft water.

EXAMPLE 11 The salt of the methyl ester of 2-tetradecyltoluoyl' sulpho'ipropionic acid was. prepared following Method A byfirst condensin tetradecyltoluene (prepared by alkylating toluene with tetradecene-l) with maleic anhydride. The tetradecyltoluoyl acrylic acid thus formed was esterified with methyl alcohol, and the resulting ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of .l%, the compound gave a wetting speed of 45 seconds and had strong sudsing and cleansing properties in soft water.

EXAMPLE 12 The salt of the n-propyl ester of dodecyltoluoyl sulpho propionic acid was prepared following Method A by first condensing dodecyltoluene (1, 3, 5, 7, tetramethyloctyltoluene) with maleic anhydride. The dodecyltoluoyl acrylic acid thus formed was esterified with n-propyl alcohol, and the resulting ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of .1%, it gave a Wetting speed of 99 seconds.

EXAMPLE 13 The salt of the n-amyl ester of decyltoluoyl sulpho propionoic acid was prepared following Method B by first condensing decyltoluene (prepared by alkylating toluene with chlorinated decane) with maleic anhydride. The decyltoluoyl acrylic acid thus formed was esterified with namyl alcohol and the resulting ester was reacted with sodium bisulphite to form the sulpho derivative. At a concentration of .l%, the compound gave a wetting speed of 50 seconds. At 0.2%, the product exhibited detergent and foaming properties.

Of the foregoing compounds, the water-soluble salts of the methyl ester of dodecylbenzoyl sulpho propionic acid; the water-soluble salts of the methyl ester of tridecylbenzoyl sulpho propionic acid; and the water-soluble salts of the methyl ester of dodecyltoluoyl sulpho propionic acid, and more particularly the sodium salts thereof, are

preferred.

" Considerable modification is possible in the method of preparing the compounds, as well as in selecting the various combinations of R1, R'1, R2, and M without departing from the scope of the present invention.

I claim:

1. As a surface active agent possessing marked detergent properties, the water-soluble salts of the benzoyl sulpho propionic acid esters corresponding to the following formula:

A B1 I O O wit-salmon? R, 8.03M

where R1 is an alkyl group containing from to 15 carbon atoms; where R1 is selected from the group consisting of hydrogen and a methyl group; where Aris selected fromthe group consisting of hydrogen and a chlorine atom when R1 is as stated and R; is hydrogen, otherwise A is hydrogen; where B is an ethylene group; where R2 is an alkyl group containing from 1 to 6 carbon atoms; whereM is a cation providing watersolubility to the product; and where the total number of carbon atoms of R2 plus carbon atoms in substituted alkyl groups on the phenyl nucleus is at least 10 but not more than 16.

2. The product of claim 1 wherein M is sodium.

3. As a surface active agent possessing marked detergent properties, a water-soluble salt of a benzoyl sulpho propionic acid ester corresponding to the following formula:

where R1 is an alkyl group containing from 11 to 14 carbon atoms; where 3/1 is selected from the group consisting of hydrogen and a methyl group; where A is hydrogen; where B is an ethylene group; where R2 is an alkyl group containing no more than 2 carbon atoms, and where M is a cation providing water-solubility to the product.

4. The product of claim 3 wherein M is sodium.

5. As a surface active agent possessing marked detergent properties, a water-soluble salt of a methyl ester of dodecylbenzoyl sulpho propionic acid.

6. As a surface active agent possessing marked detergent properties, the sodium salt of the methyl ester of dodecylbenzoyl sulpho propionic acid.

7. As a surface active agent possessing marked detergent properties, a water-soluble salt of the methyl ester of tridecylbenzoyl sulpho propionic acid.

8. As a surface active agent possessing marked detergent properties, the sodium salt of the methyl ester of tridecylbenzoyl sulpho propionic acid.

9. As a surface active agent possessing marked detergent properties, a water-soluble salt of the methyl ester of dodecyltoluoyl sulpho propionic acid.

10. As a surface active agent possessing marked detergent properties, the sodium salt of the methyl ester of dodecyltoluoyl sulpho propionic acid.

11. The method of preparing a, surface active agent possessing marked detergent properties which comprises condensing, in a Friedel-Crafts acylation reaction, a phenyl derivative selected from the group consisting of monoalkyl benzene and monoalkylmonochlorbenzene, the alkyl group of which contains from 10 to 15 carbon atoms, and monoalkytoluene, the alkyl group of which contains from 10 to 14 carbon atoms, with maleic anhydride to form the corresponding benzoyl acrylic acid, esterifying the resulting acid with a compound providing an alkyl ester group containing from 1 to 6 carbon atoms which provides, along with the carbon atoms supplied by alkyl groups attached to the phenyl nucleus of said phenyl derivative, a total of from 10 to 16 carbon atoms, and reacting said ester, at a temperature between about C. and about C., with sodium bisulphite to form the sodium salt of a benzoyl sulpho propionic acid ester.

GLEN W. HEDRICK.

REFERENCES CITED The following references are of record in the file of this patent:

v Bogert et al.: J. A. C. S., vol. 47, pp. 526-535 (1925). 

1. AS A SURFACE ACTIVE AGENT POSSESSING MARKED DETERGENT PROPERTIES, THE WATER-SOLUBLE SALTS OF THE BENZOYL SULPHO PROPIONIC ACID ESTERS CORRESPONDING TO THE FOLLOWING FORMULA: 